# Electric fields

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• Created by: argyrou
• Created on: 30-04-18 15:24
what is the equation for current?
I=Q/t
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Define Electric field strength
Force per unit charge on a positive test charge placed at that point
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What are the 2 possible different units of E?
NC-1 or Vm-1
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Define Electric potential
Work done per unit charge on a positive test charge when it is moved from infinity to that position
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What equation would you use to find the work done on a test charge whereby the charge has moved to a different potential?
W=Q(V1-V2)
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What is significant about equipotentials (2 things)
- surfaces of constant potential - lines of force of electric field cross equipotentials at right angles
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change of potential per unit charge of distance in a given direction
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What is the relationship and equation that links potential to distance
they are proportional. the equation: V/ X (x=distance)
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what is the difference between potential gradient and electric field strength?
Potential gradient= V/ X but E = - V/ X
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What is coulombs law in words (2 things)
force between 2 point charges is proportional to the product of the charges and inversely proportional to the square of the distance between charges
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What is the equation of coulombs law?
F=Q1Q2/4 r²
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An equation for Electric field strength E that consists of coulombs law
Q/4 r²
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What is the product of electric field stregth and the permitivity of free space Eε₀?
Q/4 r² = Q/A = charge/surface area of sphere = surface charge density
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what happens to 2 forces between 2 oppositely charged point charges and what is the overal electric field strength in this situation
The forces act in the same direction. The resultant electric field strength E=E1+E2
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What happens to 2 forces between 2 point charges of the same charge and what is the overall Electric field strength?
the forces will act in opposite directions. The resultant electric field strength E=E1-E2
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what happens to 2 forces that form a right angled triangle with 2 oppisitely charged point charges below the forces and how do you find the resultant electric field strength?
the forces are at right angles to each other. The resultant electric field strength E²=E1²+E2²
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What is the equation of electric potential using 4 r?
V=Q/4 r
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In an electric field is the electric potential negative or positive?
Electric potential in an electric field near a point charge can be negative OR positive according to whether the point charge is negative or positive
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what are the electric field lines between oppisitely charged particles?
0----------------------0
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What are the electric field lines between a charged point near a plate?
+ -------------------0
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What are the elecrtic field lines between oppisitely charged plates?
+ ------------------ -
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What are 2 different euations for electric field strength E?
E=F/Q=V/d
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## Other cards in this set

### Card 2

#### Front

Define Electric field strength

#### Back

Force per unit charge on a positive test charge placed at that point

### Card 3

#### Front

What are the 2 possible different units of E?

#### Back ### Card 4

#### Front

Define Electric potential

#### Back ### Card 5

#### Front

What equation would you use to find the work done on a test charge whereby the charge has moved to a different potential?

#### Back 